There are known a battery or pure electric vehicle (EV) which uses one or more electric traction motors and a hybrid electric vehicle (HEV) which combines an internal combustion engine propulsion system with an electric propulsion system. These vehicles derive all their electric power from their large capacity rechargeable battery units for power supply to traction motors and air conditioners for air conditioning in their passenger compartments. In some electric vehicle, an improvement in convenience of driving is made by charging its battery unit during regenerative braking and by restoring the battery unit to full charge with an external battery charger.
It is known from Patent Document 1 to practice so-called preparatory air conditioning (AC) operation in which, in order to maintain comfort during driving an electric vehicle after charge to restore its battery unit, the temperature and other conditions of its passenger compartment are adjusted to maintain comfort. By performing the preparatory AC operation during charge, the amount of electric power consumed for air conditioning in the passenger compartment can be saved during driving, resulting in an appreciable extension of driving range between charges in addition to improved comfort in the passenger compartment. The above-mentioned Patent Document 1 proposes performing the preparatory AC operation at a reserved time on condition that the battery charge level (State of Charge: SOC) is greater than or equal to a predetermined level.